1. Field of the Invention
The present invention relates to a semiconductor manufacturing system and to a method of operating such a system. More particularly, the present invention relates to a semiconductor manufacturing system comprising a loadlock chamber maintained at a low level vacuum, a processing chamber maintained at a high level vacuum, and a gate valve interposed between the loadlock chamber and the processing chamber.
2. Description of the Related Art
Generally, a semiconductor device manufacturing process is performed inside a processing chamber which is maintained under a high vacuum. The process is carried out with a gas having a relatively low particle density (number of gas particles per volume of the chamber).
However, when the wafers to be processed are supplied into the processing chamber, a vortex is often generated by the difference in pressure between the inside and outside of the chamber. Therefore, the particles outside the processing chamber are induced into the chamber by the vortex, thereby causing a processing failure to occur in the subsequent semiconductor manufacturing process.
Generally, the wafers associated with this process first pass through a loadlock chamber maintained at a pressure of 100 to 500 mTorr. From there, the wafers are moved into the processing chamber which is maintained at a pressure of less than 10 mTorr, which represents a much higher level vacuum than that of the loadlock chamber.
FIG. 1 shows a loadlock chamber 10 in which wafers are processed. The loadlock chamber 10 is connected to a low vacuum level pump 12 by a loadlock chamber low level vacuum line 14 in which an isolation valve 16 is disposed.
FIG. 1 also shows a processing chamber 18 in which a semiconductor device manufacturing process is performed using a processing gas. The processing chamber 18 is connected to a low vacuum level pump 24 through a processing chamber high level vacuum line 26 in which a discharge valve 20, a high vacuum level pump 22, and an isolation valve 28 are disposed in the order of flow of discharge gas.
The loadlock chamber 10 and the processing chamber 18 are connected to each other by a gate valve 30. The gate valve 30 is connected to an air source 36 by an air supply line system 35 which comprises an opening line 32 and a closing line 34. The gate valve 30 is opened when a certain amount of air is supplied into the gate valve 30 through the opening line 32, and is closed when a certain amount of air is supplied thereinto through the closing line 34.
Therefore, when the wafers to be processed are introduced into the loadlock chamber 10 under a normal atmospheric state, the isolation valve 16 is opened, and the pressure of the loadlock chamber 10 is maintained at a constant low vacuum level by the low level vacuum pump 12.
Then, a certain amount of air from the air source 36 is supplied to the gate valve 30 through the opening line 32 of the air supply line system 35. Consequently, the gate valve 30 is opened.
Then, after a certain low level vacuum is produced by the low level vacuum pump 24 with the discharge valve 20 open, the wafers are moved into the processing chamber 18. This processing chamber 18 is maintained at a high vacuum level by the high level vacuum pump 22.
Finally, the semiconductor device manufacturing process using a processing gas is performed inside the processing chamber 18, whereby by-products accumulate inside the processing chamber. However, when the gate valve 30 is opened to facilitate the transfer of wafers, a vortex occurs due to the pressure difference between the loadlock chamber 10 and the processing chamber 18 which are maintained at a low level vacuum and a high level vacuum, respectively. Therefore, the particles existing inside the loadlock chamber 10 are induced into the processing chamber 18, and the by-products accumulated in the processing chamber 18 are scattered in the processing chamber 18. Consequently, the wafers become contaminated.
In addition, the vortex applies pressure to the gate valve 30 interposed between the loadlock chamber 10 and the processing chamber 18. As a result, the life of the gate valve 30 is shortened.